Hello, new to the forum and not entirely sure where to post this, but I've been having an ongoing issue with my R53 Cooper S for two years and can't find anyone or anything to fix the issue. Hopefully someone in the Mini Community has had a similar issue and can point me in the right direction!

The Car- 2005 Cooper S with 97k Miles, Manual, 15% WMW Reduction Pulley w/ One Step Cooler Plugs, CravenSpeed Cold Air Intake, ATI Super Damper, JCW Copy Catback Exhaust, and Stage 1 Tune(Only had it tuned to try and fix issue).

The Issue- So under hard acceleration, wide open throttle from about 3k-4k RPM and up, I have a predetonation/lean condition pinging or pinking noise. I can drive it spiritedly through the gears at about 50%-75% throttle and don't get the noise but the moment I push the throttle that little bit further immediately the noise starts.

Now obviously some might say just don't go WOT but its a mini what's the fun in that? I always use 93 octane fuel from either a Shell or a Mobil 1 station so don't think bad or low octane fuel is the issue. I also recently put a couple of gallons of 110 race fuel in it and that cleared the issue. I continued to put a gallon at time of 93 on top of that diluting it, to see at what point the noise would start again and it got to a rough guesstimate of probably 95 octane to wear the noise was still not there.

I've also made sure there are no vacuum leaks on the engine, I know the charge pipe to the super charger is prone to warping and not sealing properly but mine is fine. I replaced the bypass valve with the upgraded Detroit Tuned one. I've replaced both MAP sensors, the fuel filter is new, Injectors have been cleaned and tested, Supercharger has been removed and serviced. Also recently just did new timing chain, guides and tensioner, new coil and plug wires, new camshaft position sensor, new Bosch o2 sensors, new PCV valve, and purge tank vent valve.

As you can see I've dumped a lot of money and time into this car chasing the issue and its just super frustrating. When I was a kid my father had a car with the exact same mods and never had this issue so I know I haven't gone too far with the mods, there's just something stupid I'm missing.

I look forward to hearing what people may come up with, and thank you in advance for any information you can give me!

 

Seems like a dumb question but did you change the knock sensor?

 

Have you replaced your O2 sensors?

 

Get a custom tune.

 

Are you the original owner? Any head work? Are your plugs reading normal? Had a look in each cylinder with a borescope for carbon build-up?

 

No question is dumb at this point, and sadly no I did not change it. I should have done it when I was servicing the supercharger but I didn't even realize where it was at that point.

A few people I have talked with about it, they've all said if the knock sensor was bad I would have a code right?

 

I did about about three years ago and around 10k miles ago. I had an o2 code so I changed them both. I imagine I'd have a code again if there was something wrong with them?

That's what is really frustrating about this, I never get a code.

 

That has been a thought, I just don't know a lot about tuning and there isn't anyone in my area that is a mini tuner. The stage 1 tune I have on the car was sold to me by a mini service shop that they just flashed into my ECU.

But I've also talked to Way from WMW and he has said the mods I've done, the car shouldn't need a tune. Like the PCM should be able to handle it.

 

I am the third owner. The previous two owner's were older and the car was bone stock. So I imagine there isn't any head work done. The plugs are reading normal. I have looked down the bores it didn't look out of the ordinary for a car with those sort of miles. No excess build up.

 

What about a new fuel pressure regulator and pump?

I had an issue a couple of years ago where my car would stumble at times - normally after making a turn - then wake up and go. No codes. On whim and because I knew they were original, I replaced the fuel pump and pressure regulator along with the vacuum hose to the regulator since it was rotting and crumbly. It woke my car right back up. Also, there is a fuel filter in the tank on the passenger side that might be worth replacing.

 

I have a lot more mods than you , but I also was running lean and blow my motor and had to have it rebuilt. Since then I have had it tuned 5 times.